Spirit duplicating process



DeC- 1, 1964 A. E. VAN HooF ETAL 3,159,485

SPIRIT DUPLICATING PRocEss Filed Feb. 21, 1961 5 Sheets-Sheet l INVENTORj ATTORNEYS Dec l, 1964 A. E. VAN HooF ETAL. 3,159,485'

SPIRIT DUPLICATING PROCESS 5 Sheets-Sheet 2 Filed Feb. 21, 1961 Hefe/yad, hide/led aff/d@ Jn/erred efsedes//z fyl.

INVENToRs ZerZ a/[aaj ATTORNEY De 1 1954 A. E. VAN HooF ETAL 3,159,435

SPIRIT DUPLICATING PROCESS Filed Feb. 2l, 1961 5 Sheets-Sheet 3 .a f Z L- j f l l l/ /llld/ INVENTOR5 ATTORNEY.;

United States Patent O 3,159,485 SlilRlri DUILHCA'EEJ@ PRCESS Albert Erni-elven Hoof, Berchem-Antwerp, and George Arthur Holi/oet, Mermet-Antwerp, Belgium, assignors to Gevaert Photo-Producten NN., Mortsel, Eelgiuin, a Belgian company Filed Feb. 2L 1963i, Ser. No.V @L6M Claims priority, application Great Britain Feb. 23, 31%()V l2 Claims. (Cl. 96u28).

This invention relates to a new and improved photographic method for the preparation of spirit duplicating masters. l

In our US. application Ser. No. 66,683 we have described and claimed a method of producing a printing master Asuitable for use in spirit duplicating processes according to which method a layer consisting of or containing a dyestuif is pressed against a gelatin silver halide emulsion layer in which a developed photographic image of the matter to be duplicated has been formed and which exhibits the greater. gelatin hardness in` the areas where the silver halide hasbeen reduced to silver, and the said layers are subsequently separated-with simultaneous transfer of emulsion in the other areas of said silverV halide emulsion layer onto the dyestuif layer. Following the separation of the layers in this method, the dye layer is seen to be left uncovered by the emulsion only in the areas which were, in contact with the silver image and the material comprising this selectively covered dye layerr may be used as a duplicating master. In the normal performance of this method dyestutl becomes transferred from the dye layer onto the silver halide emulsion layer in the areas Where the silver halide has been developed to a silver image so that after separation of the layers it is alsopossible to use the material having the silver halide emulsion layer (hereafter alternatively called-the photographic materia1) asa duplicating master.

According to the presentinvention we provide a new method of, producing a printing master suitable for use in spirit duplicating processes; according to thisl new method, pressing of a layer consisting of or containing dyestu against a gelatin silverhalide emulsion layer in which a developed photographic image of the matter'to be duplicated has been formed and which exhibits the 'reater gelatin hardness in the areas where the silver halide has been reduced to silver, and subsequently separatingsaid layers with simultaneoustransfer of emulsion in the other areas of said silver halide emulsionzlayer onto the dyestutf layer is carried out in theY same manner as in the method aording to our United States patent' application Serial No. 66,083. Thereafter, however, the material comprising the yselectively covered dye layer is pressed against a receptor sheet, eg. a sheet of ordinary invention and certain of the manipulative procedures utilized therein may be conveyed by the accompanying drawings in which:

FIG. l is an illustrative embodiment of the present method carried out with a direct-reading opaque original using reflex exposure and showing the materials in several stages and the processing steps between those stages, all with appropriate captions;

FIG. 2 is a similar embodiment carried out with a consisting of one or more aliphatic alcohols.

negative transparency using exposure through the transparency;

FIG. 3 is a diagrammatic view in side elevation of one form of apparatus for effecting the developing and pressing steps of the present method; and

FIG. 4 is a view similar toFIG. 3 of a modified form of apparatus. y

It will be appreciated that FIGS` l and 2 are more or less idealized portrayals of the present invention, the thickness ot theiseveral-layers and supports, for example, being considerably exaggerated for sake of clarity and by no means necessarily representing what actually occurs in practice. In these figures, the following convention has been adopted to depict the dierent conditions of the emulsion: Standard cross-hatching indicates undeveloped,

unhardened emulsion material, double cross-hatching indicates emulsion material that has'beenhardened by tanning development, and added stippling indicates emulsion material that has been developedv to contain silver metal grains.

As set forth in our Unitedv States patent application Serial No. 66,083, the dye layer must, of course, be of such composition that the dyestutf is capable of being transferred to` print paper when this is contacted with the master in the presence of a suitable liquid, e.g., a liquid as usually employed for spirit duplicating and mainly By Way of example, good results have been obtained with certain of the commercially available dye sheets used in the preparation of spirit duplicating masters bymechanical means (e.g., by type-Writing). Good results have not been obtained with all of such dye sheets. In particular sheets in which the dyestul layer iscovered by a hydrophobic protective layer, eg., a wax layer, should not be used. However, a few simple tests with different dye sheets will serve to show whichy are suitable. We have obtained good results with certain dye sheets having a dyestulf layer containing an alcohol soluble dye, eg. crystalviolet, and aI waxy or viscous hydrophilic binder, the dye layer oontaining noprotectivek supercoat. We refer by way of example of suitable commercially available dye sheets, to aY hectographic carbonV paper manufacturedby Gnther Wagner Pelican Werke, Hannover, and designated.Pel.-ican 991 U 25, andV a fluid duplicating carbon known as Standard, sold by Standard Duplicating MachinesV Corporation, Everett, Mass., United States.V of America.

It isv not necessary (although it is preferred) for the dye layer used in a method accordingV tothe invention to be-part of a sheetv material, e.g., a dye-coated paper. For example, a suitable dye layer may be applied to a. plate or other rigid supporting base and the image-bearing emulsion layer may be rolledl or otherwise brought into- Contact with suchf dye layer. y

The photographic material may, e.g. comprise a lightsensitive unhardened or substantially unhardenedgelatin silver halide emulsion layer coated onto a flexible support, e.g. paper. form may be used for recording a multiplicity of images successively or simultaneously preparatory to the production ofY corresponding printing masters; itis also possible rto use as the dyestuif material a material in roll'formso that a complete series rof latent imagesK on the photographic material Vmay be developed and the printing masters may be produced in a continuous operation. However, normally it is more convenient for the photographie material and the dyestuf material to be in the .form of sheets in a size suiicient for recording single images.

The photographic material maybe prepared for contact with the dyestutf layer by exposure of the lightsensitive layer to the matter to be duplicated followed by a panning development.

If desired photographic materialin roll The primary intended use of the method according to the invention is for document copying. The duplicating masters are generally prepared from positive originals, or from negative records of positive originals. The invention, however, is not limited to the preparation of masters for producing positive duplicated copies.

For preparing a printing master which will produce positive readable copies of an original text, it is necessary in the event that the receptor sheet is to be used as printing master to expose the light-sensitive material in such a way that by the development, a laterally reversed negative silver image of the original is obtained on this lightsensitive layer. This result may be achieved by reiiectographically exposing the `light-sensitive layer to the original. Other methods are available, however, for obtaining a laterally reversed silver image which are known to those skilled in the art of document reproduction. If the dyestuif material is to be used as printing master the photographic material is exposed in such a way that the developed photographic image is a readable positive image. It will be understood, however, that these rules mainly only apply when reproducing reading matter. The invention is not limited to the preparation of masters for reproducing reading matter, and in some cases, eg., `in the reproduction of drawings, it is not always necessary for the master copy to be laterally reversed with respect to the original. Neither is the invention limited to the preparation of masters for producing positive duplicated copies.

Having regard to the foregoing, it will be understood that the photographic image referred to in the principal claim of this specification may be a positive image, a negative image, a laterally reversed image or a directreading image. It is also to be understood that this image may be larger or smaller than or of the same size as the matter to be duplicated.

The exposed light-sensitive emulsion layer may be subjected to tanning development, e.g. by using a solution of tanning developing agent. Polyoxybenzenes, especially pyrocatechol and pyrogallol, which are used -in an alkaline medium, :are mostly used as tanning developing agents and these compounds are very suitable for use in preparing developing `an exposed photographic material for use in the method according to the present invention. Various alkalis are suitable; alkali carbonates or alkali hydroxides are usually used in practice. We recommend that a softening agent for gelatin (eg. urea) be incorporated in the developing bath and/or in the silver halide emulsion of the photographic material used in carrying out the invention.

A development accelerator may be used if desired, e.g. a quaternary ammonium compound, a quaternary pyridinium compound or one or the other quaternary salts of organic nitrogen bases specilied in the specification of United States patent application Serial No. 37,101.

According to a preferred embodiment of the present invention, a photographic material is used which contains a tanning developing agent, e.g., pyrogallol or pyrocatechine or one of the compounds proposed in our United Kingdom patent specification 812,673 and tanning development of the exposed emulsion layer is effected in an alkaline solution, which does not itself contain a tanning developing agent. The yalkaline solution may incorporate a softener for gelatin (eg. urea) as before referred to and the development may be effected at increased temperature. A favorable developing temperature of the liquid containing alkali and urea is from 28 to 30 C. In the liquid wherein development takes place, an alkali carbonate is preferably used as alkali; alternatively or in addition some other alkaline compound, e.g. sodium phosphate, triethanolamine, alkalihydroxides, a bicarbonate etc. may be used. Due to the developing solution being free of any tanning developing substance, deterioration of the developing solution by oxidation of the tanning agent under the influence of the oxygen in the air is completely avoided, even when the development is carried out at relatively high temperatures. Accordingly, the development can be carried out at higher temperatures so that the development time can be shortened.

Although it is possible to prepare a printing master by bringing the exposed photographic material and the dyestuff material together before the development, introducing the two materials together into the developing bath and subsequently pressing them firmly together before separating them we have so far not obtained good quality masters by proceeding in this way and it is advisable to bring the two materials together after the treatment of the photographic material in the developing bath. Preferably the pressing together of the materials is effected las the photographic materials leave the tanning developer. This may be accomplished either by means of one or more pairs of rollers or by means of a roller or rollers and a cooperating non-rotating part or parts, mounted against the exit point from the developer. The roller or rollers, and or the non-rotating co-operating part or parts where provided, may be heated. Alternatively or in addition, means may be provided for heating the developer.

In our United States patent application Serial No. 66,083 we have described automatic and semi-automatic methods of preparing the new deplicating masters wherein the dyestuif layer 'and photographic copy are pressed together as the said copy is withdrawn from the tanning development bath. Appanatus according to the said United States patent application Serial No. 66,083 may be used in carrying out the present invention. A very suitable apparatus for carrying out the development of (the light-sensitive material and pressing this against the carbon paper is that shown in FIG. 2 of the drawings accompanying the said United States application Serial No. 66,083 which figure is reproduced as FIG. 1 of the drawings accompanying the present application. Referring to this figure, 1 represents a tank for containing the alkaline solution in which tanning takes place. A top space 2 is provided which is separated from the liquid; 3 and 4 are pressure rollers. An electric resistance 5 is provided under the developer compartment for heating the liquid in the tank. This resistance can be coupled t0 a thermostat in order to maintain the liquid at a constant temperature, e.g. between 28-30 C. The roller 3 is mounted so that it can be displaced away from roller 4. In order to prepare la duplicating master, the roller 3 is moved away from the roller 4 and a light-sensitive sheet A which has been exposed is passed between the rollers into developing tank 1. Whilst the photographic material A is being developed, a hectographic dye sheet B is slipped into the top space 2. The length of the sheets A and B is such that when they are inserted as shown into the developer space and the top space of the tank, end portions orf the two sheets extend between the rollers 3, 4.

Before withdrawing sheet A from the developer, the roller 3 is moved into operative position so as to grip the sheets A and B together against roller 4. The developed photographic material A and dye sheet B are now drawn between the rollers. As the sheets travel between the rollers superfluous liquid is pressed away and the two sheets leave the apparatus adhering together in inimate face to face contact. The sheets A and B are subsequently stripped apart and the dye sheet is pressed against a paper sheet. Thereafter the paper sheet is stripped o and iS ready for use as -a duplicating master in a spirit duplicating process. If desired heating can take place by means of the pressure roller(s) 3 and/or 4. The space 2. is not necessarily closed; sheet B may simply rest on the top of a one-compartment tank. All that is necessary is a support surface enabling the dye sheet B to be placed in ready position behind the rollers 3 and i in such a way that after development of the material A, the materials A and B can be together pulled between the pressure rollers. One or each of the rollers can be replaced by a rubber scraper. One of the rollers can also be replaced by a flat steady bar. The rollers can be operated either electrically or manually. If desired the developer space of tank 1 can have its entrance sealed by resiliently mounted closure means or by wedges of synthetic substance in order to reduce oxidation of the developer liquid by contact with the air.

It is possible that as the materials A and B are pressed together the squeezed liquid dissolves a little dyestuff of the hectographic dye sheet andf dirties the liquid in the tank. The apparatus can be provided with a small drip tray or other container for receiving this squeezed out liquid. Another'way of keeping the liquid in useful condition for as long as possible so that the development of light-sensitive material can proceed without disturbance is to add to the alkaline liquid a precipitating agent for the basic dyestut of the hectographic dye sheet. Organic precipitating agents have been found very useful for this purpose. In general compounds are suitable which possess a relatively great anion such as for instance the watersoluble salts of diamine silbene derivatives (cf. our Dutch Patent 89,134) trichloro-acetic acid, salicylic acid, nitrophenol, benzene and toluene sulphonic acid etc.

Other substances may be added to the solution of alkali and urea, e.g. quaternary nitrogen compounds for activating or accelerating the development (e.g., those disclosed in our U.S. patent application Ser. No. 37,101). Further, if desired, the sticking vproperties ofthe gelatin can be influenced by the use of hygroscopic substances such as for instance glycerol, glycols, polyglycols, potassium` carbonates, wetting agents etc. Organic solvents which are compatible with the alkaline liquid can likewise be added e.g. in amounts of 25 to 100 cm.s to promote the transfer of unhardened gelatinV onto the carbon paper. Examples of such solvents are: ethanol, methylglycol, isopropylalcohol, Carbitol, dioxane, butyrolactone etc.

According to a preferred embodiment of the present invention, a sheet material having an unhardened or substantially unhardened light-sensitive silver halide emulsion of the negative type is reilectographically exposed to an original to be reproduced. After exposure and developient in a tanning developer, the photographic material is pressed against a dye-sheetV of the type hereinbefore referred to composed of or containing a dyestutf layer.

' Although not essential, it is advisable for obtaining sharp prints, to heat` the two adhering materials for a while to a temperature of 35 to 40 C., e.g. by pressing the photographic material with its back-side against a heated plate for a few seconds. Thereafter the photographic material is separated from the dyesheet. A gelatin relief image, corresponding to the lightly. orinon-tanned gelatin parts of the emulsion is found adhering to the dye sheet. After a few seconds, the dye sheet is pressed against a sheet of ordinary paper. After a few seconds, the dye sheet is stripped oif and discarded, whilst the sheet of paper shows now a dyestuff-containing laterally reversed image. This sheet of paper can be used as duplicating master sheet on a spirit duplicator.

Accordingto Ianother embodiment of the present invention, a photographic material having an unharidened or substantially unhardened light-sensitive silver halide emulsion of the negative type, i.e. an emulsion which on exposure to a text Iand development gives a silver image in the exposed areas is used. Onto this light-sensitive layer is projected a negative microfilm record of a text or drawing, taking care that the negative in the enlarger be turned with its back-side to the light source, so that by development of the photographic material a positive direct-reading image of the original text or drawing is obtained. After development inY a tanning developer,` the photographic material ispressed against dye sheet of a commercial type hereinbefore referred to; the two materials adhering together are heated for a while, e.g. by pressing the back-side of the photographic material against a heated plate. Then the photographic material is stripped off from the dye sheet and is discarded. The dye material 6- can now be used as a master sheet in a spirit duplicator to yield printed positive copies of the original.

In ta modication of the embodiment just described a negative microlrn record of a text or drawing is projected onto a photographic material with a silver halide emulsion of the direct-positive type, taking care that the negative in the enlarger isturned with its image side to the lightsource, so that by development of the photographic material a negative counterpart, i.e. laterally reversed negative image of the original text'or drawing is obtained. After development in a tanning developer the photographic material is pressed against a dyestutf material such as a dye sheet as hereinbefore referred to and subsequently stripped olf; the dyestuff materialV is pressed against a sheet o-f paper, which is stripped off and can be used in a spirit duplic-ator to yield printed positive copies of the original.

The invention is not limited to the exposure methods described above. It will be clear to those skilled in the art of document copying Vthat other variants are possible.

The invention will be further illustrated-by selected specific examples. (In Examples l and 4 the developer solution constituents are given in the order in which we in practice use them to make up the solutions in question.)

Example 1 To a contrasty silver halide emulsion of the type which by image-wise exposure and development gives a negative, are added 40 g. of urea per kg. of emulsion. The emulsion` is applied to paper an ddried; The light-sensitive paper obtained isV retlectographically exposed to a positive original, and thereafter developed for 35 seconds at 20 C. in a tanning developer of the following composition:

Water cm.3 800 Urea g 60 Sodium carbonate (anh.) g-- 30 Pyrocatechol -g-- 6 Ascorbic acid borate potassium salt`` g-- 2 Water to cm.3 1000 whereby the exposed areas of the emulsion layer are blackened and hardened and form a negative laterally reversed image of the original. The emulsion layer comprising the hardened and unhardened areas is pressed against -a dye sheet of a type generally used in the preparation of master sheets for spirit duplicating by mechanical means, for instance by typewriting, and the dye-stuff layer of which is not provided with a protective supercoat, and the two materials are squeezed together between two rubber rollers. The two materials adhering together are fora while pressed with the back side of the photographic material against a plate heated at 35 to 40 C. Thereafter, the photograpldc material is stripped olf and discarded. After 5 to 60 seconds the dye-sheet is pressed against a sheet of ordinary paper. After l minute, the sheet of paper is stripped off from the dye-sheet. This sheet of paper carries now a dyestulf-containing positive but laterally reversed image of the original, and can be used as duplicating master sheet from which tens of prints can be obtained by spirit duplicating, e.g. by means of one of the commercially available spirit duplicators.

Example 2 A photographic material which is of the same composition as the photographic material used in Example 1, is reflectographically exposed to the original to be reproduced, and developed for 20 seconds at 28 C. in the developer of Example l. The developed photographic material is then pressed against a hectographic dye-sheet as in Example l, without heating however. After 5 to l0 seconds this sheet is stripped off, and the dye-sheet is further pressed against a sheet of ordinary paper as in Example 1. This paper sheet is then stripped off from the dye-sheet and can be used as a duplicating master sheet in the same way as the paper sheet in Example l.

Z Example 3 To a 135 g./sq. m. paper strip is applied a very contrasty silver halide emulsion of the type which after imagewise exposure and development gives a negative, to which was added per litre of emulsion:

Urea 50 Pyrocatechinol Potassium metabisulphite 2 After gelling and drying, this material A is reflectographically exposed. Development occurs for seconds at 22 C. in the following solution:

Anhydrous sodium carbonate g 30 Water to cm.3 1000 The further procedure is as in Example 1, thus: pressing of the photographic material against a dye-sheet, heating, stripping off the dye-sheet and discarding the photographic material. The dye-sheet is pressed against a sheet of ordinary paper, the latter is stripped off, and can be used as a duplicating master sheet in the same way as the paper sheet in Example l.

Example 4 A photographic material A, which is of the same composition as the photographic material of Example 1, is reilectographically exposed to the original and developed for 20 seconds at 22 C. in the following solution:

Water cm.3 800 Urea g 90 Anhydrous sodium carbonate g 30 Pyrocatechol g 6 Potassium salt of ascorbic acid borate g 2 p-Nitrobenzylpyridinium chloride g 1 Water to cm.3 1000 After development, the photographic material is pressed for 20 seconds against a hectographic dye-sheet as in Example 1. Thereafter the dye-sheet is stripped off and is further pressed against a sheet of ordinary paper. The latter is stripped off from the dye-sheet and can be used as duplicating master sheet from which tens of prints can be made by spirit duplicating.

Example 5 To a contrasty silver halide emulsion of the type which by image-wise exposure and development gives a negative are added g. of urea and 15 g. of pyrocatechol per kg. of emulsion. The emulsion is applied to paper and dried. The light-sensitive paper obtained is reflectographically exposed to the original to be reproduced. It is then developed and pressed against a hectographio dyesheet. For this purpose use is made of the apparatus diagrammatically illustrated in FIG. 4 of the accompanying drawings, in which:

W=a thermostatically heated resistance for heating liquid in tank T at 28-30o C.

A=the light-sensitive material B=hectographic dye-sheet G=guides for material 1 and 2=rubber rollers One of the rollers can be replaced by a flat narrow plate so that squeezing occurs between a rubber roll and a steady wall. At least one of the rubber rollers can be replaced by a rubber scraper. The tank T of this apparatus is filled with the following solution:

G. Sodium carbonate anhydrous 30 Urea Water to 1000 cm.3.

The exposed photographic material is immersed for 20 seconds into the solution and afterwards, by turning the rubber rollers the sheet is removed from the apparatus and at the same time pressed together With the hectographic dye-sheet. After 30 seconds, the dye-sheet is stripped off and pressed against a sheet of coated paper. This pressing together can again occur by leading the dye-sheet together with the paper sheet between the rubber rollers. After drying, the dye-sheet is stripped off from the sheet of coated paper. The latter can now be used as master sheet for producing more than prints of the original in a spirit duplicator.

Example 6 A light-sensitive photographic material of the same composition as the photographic material used in Example 5 is refiectorgraphically exposed. This photographic material is developed and pressed against a hectograpln'c dye-sheet, whereby an apparatus as described with reference to FIG. 3 of the accompanying drawings is used, but the solution wherein development is carried out consists of:

Sodium carbonate anyhdrous 30 Urea 60 Leucophor B (registered trademark for an optical bleaching agent of Sandoz) 1 Water to 1000 cm?.

Further treatment occurs as described in Example 5.

Example 7 A photographic material which is of the same composition as the photographic material used in Example l is exposed in an enlarger to a negative microfilm record of a printed text, the back side of the microfilm being turned to the light source, and developed for 20 seconds at 28 C. in the developer of Example 1. The further procedure is as described in Example 2: pressing of the photographic material against a hectographic dye-sheet, stripping off the dye-sheet, pressing the dye-sheet against an ordinary paper sheet and stripping off this paper sheet. The ordinary paper sheet is discarded, and the dye-sheet can be used as duplicating master from which tens of prints can be made by spirit duplicating.

Example 8 A photographic material of the same composition as the photographic material used in Example 3 is exposed as described in Example 7. Development occurs for 30 seconds at 22 C. in the following solution:

Anhydrous sodium carbonate g 30 Water to cm.3 1000 The further procedure is as in Example 1, thus: pressing of the photographic material against a dye-sheet, heating, stripping off the dye-sheet, pressing of the dye-sheet against an ordinary paper sheet, and stripping off this paper sheet. The ordinary paper sheet is discarded, and the dye-sheet can be used as duplicating master as described in Example 7.

Example 9 From a positive original to be printed is first made a transparent positive in the following way: a. sheet 0f negative material intended for application of the silver complex diffusion transfer process, commercially available as Gevacopy negative, is reflectographically exposed to the original. The Gevacopy negative is then brought together with a sheet of Gevacopy positive film, into an apparatus filled with developer for the silver complex diffusion transfer process. After leaving the apparatus the sheet of Gevacopy positive film is stripped off from the sheet of Gevacopy negative. The Gevacopy negative is discarded and a positive transparent print of the original is lef-t. As photographic material is used a support on which is coated a silver halide emulsion of the type which on exposure gives a direct positive as described in Example 4 of our United Kingdom patent specification No. 821,251. Before applying the emulsion to the base, 50 g. of urea per kg. are added in order to prevent the hardening of the emulsion layer. tive is brought into contact with the photographic material the emulsion side of the transparent positive beingV turned to the light-source. Development, pressing the photographic material against the dye-sheet, stripping ofi the photographic material, pressing the dye-sheet against an ordinary paper sheet, and stripping oit" the paper sheet then follows as in Example 1 hereof. The remaining dyesheet can be used as master sheet on a spirit duplicator for obtaining tens of prints.

We claim:

1. A method of producing a printing master, adapted to produce direct-reading copies of a direct-reading original to be copied, for'use in a spirit duplicating process, by the steps comprising:

(1) Exposing a silver halide emulsion layer to the original to be copied to produce on said layer a latent photographic image of said original;

(2) Developing said emulsion layer with a developing solution in the presence of a tanning development agent to produce a developed photographic image of said original having increased gelatin hardness in the areas Where the silver halide has been reduced to silver;

(3) Pressing the developed emulsion layer while still moist with said developing solution and with the hardened and unhardened areas of said layer intact and in substantially coplanar relationship .directly against a hectographic dye-sheet bearing a layer containing a hectographic free of protective coa-ting;

(4) Separating said sheet and layer with simultaneous transfer to said dye-containing layer of a stratum of emulsion from those areas of the emulsion layer Where the silver halide is unreduced;

(5) Pressing said dye-containing layer with the transferred stratum of emulsion thereon against -a receptor sheet, and

(6) Seperating said dye-sheet and said receptor sheet with simultaneous transfer to said receptor sheet of the stratum of emulsion from said dye-containing layer together with adherent material from said dyecontaining layer whereby said receptor sheet is provided with a relief imagey of the original comprising external dye-containing material adhered to said receptor sheet through a stratum of emulsion.

The transparent posii 2. A method according to claim 1 wherein at least said emulsion layer is heated to a temperature of about 35-40 C. While being pressed against said dye-containing layer.

3. The method of claim 1 wherein said original to be copied bears indicia on an opaque support and said photographic exposure step (1) is carried out reiiectographically.

4. The method of claim 1 wherein said exposure step is carried out to produce a laterally reversed image of said original to be copied, said image being negative relative to the original.

5. The method of claim 1 wherein said silver halide emulsion layer contains a softening amount of urea.

6. The method of claim l wherein said tanning development agent is pyrocatechol.

' 7. A method according to claim 1, wherein the silver halide emulsion is of a type which after image-wise exposure and development gives a silver image in the eX- posed areas and wherein the layer formed by said silver halide emulsion contains a tanning developing agent.

8. A method according to claim 1, wherein the said photographic image is obtained by means of tanning developrnent in the presence of urea as a softener for gelatin.

9. A' method according to claim 1, wherein the said photographic image is obtained by means of a tanning development at 28 to 30 C. in an aqueous solution containing alkali and urea as a softener for gelatin.

10. A method according to claim l, wherein the dye layer is pressed against the gelatin silver halide emulsion layer as the latter emerges from a development bath.

11. A method according to claim 1, wherein the receptor sheet is used as printing master after its separation from the dyestuff layer.

12. A method according to claim 1, wherein a dyecontaining layer is used as printing master after its separation from the receptor sheet.

References Cited in the file of this patent UNITED STATES PATENTS 2,852,371 Kendall Sept. 16, 1958 2,903,964 Taylor Sept. 15, 1959 3,054,692 Newman et al Sept. 18, 1962 

1. A METHOD OF PRODUCING A PRINTING MASTER, ADAPTED TO PRODUCE DIRECT-READING COPIES OF A DIRECT-READING ORIGINAL TO BE COPIED, FOR USE IN A SPIRIT DUPLICATING PROCESS, BY THE STEPS COMPRISING: (1) EXPOSING A SILVER HALIDE EMULSION LAYER TO THE ORIGINAL TO BE COPIED TO PRODUCE ON SAID LAYER A LATENT PHOTOGRAPHIC IMAGE OF SAID ORIGINAL; (2) DEVELOPING SAID EMULSION LAYER WITH A DEVELOPING SOLUTION IN THE PRESENCE OF A TANNING DEVELOPMENT AGENT TO PRODUCE A DEVELOPED PHOTOGRAPHIC IMAGE OF SAID ORIGINAL HAVING INCREASED GELATIN HARDNESS IN THE AREAS WHERE THE SILVER HALIDE HAS BEEN REDUCED TO SILVER; (3) PRESSING THE DEVELOPED EMULSION LAYER WHILE STILL MOIST WITH SAID DEVELOPING SOLUTION AND WITH THE HARDENED AND UNHARDENED AREAS OF SAID LAYER INTACT AND IN SUBSTANTIALLY COPLANAR RELATIONSHIP DIRECTLY AGAINST A HECTOGRAPHIC FREE OF PROTECTIVE COATING; (4) SEPARATING SAID SHEET AND LAYER WITH SIMULTANEOUS TRANSFER TO SAID DYE-CONTAINING LAYER OF A STRATUM OF EMULSION FROM THOSE AREAS OF THE EMULSION LAYER WHERE THE SILVER HALIDE IS UNREDUCED; (5) PRESSING SAID DYE-CONTAINING LAYER WITH THE TRANSFERRED STRATUM OF EMULSION THEREON AGAINST A RECEPTOR SHEET, AND (6) SEPERATING SAID DYE-SHEET AND SAID RECEPTOR SHEET WITH SIMULTANEOUS TRANSFER TO SAID RECEPTOR SHEET OF THE STRATUM OF EMULSION FROM SAID DYE-CONTAINING LAYER TOGETHER WITH ADHERENT MATERIAL FROM SAID DYECONTAINING LAYER WHEREBY SAID RECEPTOR SHEET IS PROVIDED WITH A RELIEF IMAGE OF THE ORIGINAL COMPRISING EXTERNAL DYE-CONTANING MATERIAL ADHERED TO SAID RECEPTOR SHEET THROUGH A STRATUM OF EMULSION. 